Process and method of disintegrating metals in a ball mill or the like



Patented Jan. 12, 1926.

UNITED STATES PATENT OFFICE.

GRAIING COMPANY, INC., OF NEW YORK, N. Y., .A CORPORATION OF NEW YORK.

PROCESS AND METHOD OF DISINTEGRATING METALS IN A BALL MILL OR THE LIKE.

No Drawingm Application filed March 25, 1919, Serial No. 285,055.Renewed June 3, 1925.

To all 7.0120711 it may concern.

Be it known that I, Evnnn'r'r citizen of the United States. residing atPassaic, in the county .of Passaic and State of New Jersey, haveinvented certain new and useful Improvements in Processes and Methods ofDisintegrating Metals in a Ball Mill or the like, of which the followingis a specification. v

This invention relates to the reduction of metals to a finely dividedcondition in the nature of a dry powder or dust, in which the individualparticles are in the form of minute relatively flat flakes, such as maybe' used for the production of metal paint ,etc.

The practice of the invention may involve a preliminary disintegrationof the metal. and then subjecting it to the mechanical ac tion of steelballs or the like in an ordinary ball-mill, whereby. disintegration iscompleted to the desired fineness.

One of the objects of the invention is to facilitate, in a mechanicalsense, the breaking up of the particles of metal into smaller particleswithout relative loss of the fiat surface of the particle, and wherebythe time and the power consumed in the disintegration are greatlyreduced.

A further object is to conduct the disintegration aforesaid with theparticles of the metal under treatment well covered with a liquid in thenature of an oil or its equivalent, this liquid having the property (1)Of protecting the metal under treatment against the eifects ofatmosphere dnr-, ing the disintegration, as for instance oxidation,explosion and the like;

Of lubricating the metal particles so that the reduction of them by theballs or other disintegrating means is more easily and quicklyaccomplished;

(3) Of forming with the metal particles,

a mixture like a cream, sludge, or emulsion which is tenacious, cohesiveand adhesive, and resistant to separation or segregation of itsconstituents and to the destruction of it own continuity, and whichaccordingly maintains a substantially uniform, continuous andhomogeneous character during the disintegration, a mixture in which thetendency of the metal particles to settle out is minimized; I

(4) Of constituting a vehicle for the metal particles which will adhereevenly to the surfaces of the mill and of the balls by J. HALL, a"

the met means of which the reduction or disintegration is carried on, sothat from the im act of ball against ball or ball against m1 l-wall atany point there will .alsoresult the flattenmg or reduction of aparticle or particles of metal carried in the oily sludge or cream, theopposing surfaces,

WhlCll over-spreads the sludge being of such Wlll coat the balls, but;not so thick as to unduly cushion the blow of the balls when they cometogether or strike the mill-wall;

(5 Of having a boiling point sufliciently consistency that it during thedisintegrating process, but not so high that there will be difficulty inremoving it completely later on when the disintegration has beenfinished;

(6) Of being chemically inert, throughout the operation, to the metalunder treatment, and preferably also non-inflammable;

being easily removed by eva oration from the metal particles afterdisintegration is completed, but leaving the ticles with a coating ofgrease.

Still another, and more specific, object of the invention is to providea protective vehicle or covering for the metal particles while they arein a ball-mill or the like and for the attainment of the objectlast-above final reduction or comminution can more readily be carriedon, as by turning it down in a lathe, whereby to produce chips orshavings of a size to facilitate further reduction. During thispreliminary reduction the metal may be maintained entirely covered witha liquid as hereinafter described, a convenient way .of accomplishingthis being to immerse the metal and cutter 1n a bath of the li uid. Toinsure that the liquid shall not reach oilmg or decompositiontemperature on account of the heat necessarily speed production,

quantity. The final reduction is accomplished referably in a ball-mill,in which al particles are subjected to the hammering action. of ballagainst ball and ball 0 high to prevent extensive loss by vaporiza-'par- resulting from highit may be continuously renewed, or initiallysupplied in sufiicient against mill-wall. During this operation themetal is kept well covered with a liquid having the roperties above setforth. I have had- 00 results with a mixture of varnoline a petroleumfraction oil with a boiling point between 307 and 405 F), and stearine,in the proportion (assuming that there is 1.5 lb. of metal, as copper,under treatment) of 0.75 lb. of varnoline, 50.00 lb. of balls, andstearineabout 0.33% of the weight of copper. I This liquid protects themetal against the effects ot'atmosphere, lubricates the particles sothat their further reduction is facilitated, carries and supports theparticles by reason of its creamy consistency, against the tendency ofthe particles to settle out and separate, and adheres evenly to thesurfaces of the mill and of the balls, so that from the impact of ballagainst ball, or ball against mill-wall at any point there will resultthe flattening or reduction of a particle or particles of metal carriedin the oily vehicle which over-spreads the opposing surfaces. Thisliquid has a boiling point suiiiciently high to prevent extensive lossby vaporization during the disintegratin process, but not so high thatthere will be difiiculty inremoving it completely later on when thedisintegration has been finished. The liquid is chemically inert to themetal under treatment and to the metal of the mill and the balls, andmay substantially non-lnflammable b tion of suitable chemicals, as orinstance carbon tetrachloride.

Upon completion of disintegration the contents of the mill are subjectedto evaporation, preferably under conditions of vacuum, so that thevarnoline goes off at a comparatively low temperature, thus minimizingthe danger of the metal catching fire on removal from the dryer whilehot. In the process of vacuum drying, of course, the distillate may berecovered for re-use. After the oil has all gone oil, the stearineremains in the shape of a coating on the particles. Such a coating isbelieved to be desirable where the powder is to be used for decorativepurposes.

I prefer to use polished steel balls in the milling operation, because Ihave found that roughened balls tend to break up the metal particleswithout flattening them to the de sired extent. a

It will be appreciated that as the disintegration of the metal proceeds,the total surface area of the metal particles is enormously increasedand for that reason I may begin the disintegration with a .suflicientamount of the liquid and add other additional quantities of varnoline orstearine, or both, at intervals as the disintegration goes on. And whenthe disintegration has been carried out to the desired extent I---mayadd a considerable amount of the varnoline in order to make the contentsof the mill more if desired be renderedthe addi{ fluid and utilize theliquid as'a vehicle for carrying the metal to the filter and/or dryer,

where of course the oil is driven 0E and recovered for re-use.

In grinding the metal it is apt tobeeom e.

warm due to the mechanical action, and if the liquid has not beenrendered non-inflame mable there will be a -short interval of time whenthere is a possibility of explosion of the oil vapors, if thereis-access ofatmosphere. To obviate the possibility of such 3.1;,

explosion I contemplate exhausting the air from the mill, its placebeing takenb the oil vapors which will be given off. r of course asimple remedy will-be to make the liquid non-inflammable or to use anon-inflammable liquid in the first instance. Furthermore, I contemplatekeepingdown the temperature of the'mill during operation by a spray ofcooling water or the like. In the case of continuous grinding, that is,where the oil and metal are fed and discharged continuously and the oilreturned after being separated from the metal, the temperaturemay bemaintained by some outside cooling means, or by circulation throughpipes which are air cooled or water cooled, or any other desirablemeans. While this cooling is not strictly essential to operation, itdoesundoubtedly lessen the risk of firel'n the case of inflammableliquids, and prevents loss of liquid from evaporation whether the liquidis inflammable or non-inflammable.

I claim c .1. The art of manufacturing metal dust which consists inmechanically disintegrating the metal, while keeping it covered with iby vaporization; and thereafter freeing the.

disintegrated material from the liquid by evaporation of the liquid, toproduce a dry metallic powder.

2. The art of manufacturing finely divided metal in the form of minuterelatively fiat flakes, which consists in subjecting the metal to theaction of a ball mill or the like, while keeping it covered with alubricating liquid which protects the metal against the eiiects. ofatmosphere and is inert to the metal, and which has a boiling point highenough to prevent excessive loss by vaporization during thedisintegration, but not so high that there will be diiiiculty in itsseparation later from the metal by vaporization; and thereafterevaporating the liquid from around and between the particles to producea dry metallic powder.

3. The art of manufacturing finely divided metal in the form of minuterelatively 'fiat flakes, which consists in subjecting the metal to theaction of a ball mill or the like, while keeping it covered with alubricating 1i uid which protects the metal against the eli ects ofatmosphere and is inert to the metal, and which has a boiling point highenough to prevent excessive loss y vaporization during thedisintegration, but not so high that there will be diificultyin itsseparation later from the metal byvaporization, preventing decompositionof the liquid during the disintegratiomland thereafter evaporatng theliquid from around and between tlhe particles to produce a dry metallicpower. 7

4. As a step of the process of disintegrating metals in a bell-mill orthe like, keeping the metal under treatment covered with a liquidconsisting of a avin 'a definite boiling with the metal particles, inthe operation of the mill a homogeneous mixture like a thick cream,sludge or emulsion which is tenacious, cohesive and adhesive andresistant to separation or segregation of its constituents and to thedestruction of its own continuityand which maintains a substantiallyuniform, continuous and homogeneous character during the disintegration.

5. The method of disintegrating metal in a ball mill or the like whichcomprises keeping the metal well covered with a liquid com rising alarge proportion of a relatively point which forms rea ily vaporizableoil, and a small proportion of a grease having a boiling point higherthan that of the oil, and when the disintegration is completed, drivingoff from the metal particles the v readily vaporizable oil withoutdisturbing the grease.

6. As a step in the process of disintegrating metals in'a ball-mill orthe like, keeping the metal particles well. covered with a liquidcheniically inert to the metal and having a boiling point smfiicientlyhi h to prevent extensive loss by evaporization uring the disintegratinggirocess, but not so hi h that there will be di culty in removing itcompletely plurality of ingredients against ball or ball againstmill-wall at any point there will result the flattening or reduction ofa particle or articles of metal carried in the sludge whic over-spreadsthe opposing surfaces, the sludge being of such consistency that it willcoat the alls, but not so thick as to unduly cushion the blow of theballs when they come together or strike the mill-wall; and eflectin searation of the metal particles from t e liquid after the disintegrationhas been com leted, to leave the metal particles in a su stantially drystate.

7. The method of disintegrating metals, consisting'of the steps setforth in claim 3 with the additional step of adding a sufficient amountof oil to the contents of the mill when the disintegration is completednecessary for carrying the metal particles out of the mill.

8. The process of manufacturing metal powder which-consists inmechanically disintegrating metal, while kee ing it covered with alubricating liquid which protects the metal against the effects ofatmosphere and is inert to the metal, and which has a boil ing pointhigh enough to prevent excessive loss by vaporization during thedisintegration, but not so high that there will be difficulty in itsseparation later from the metal by vaporization.

In testimony whereof I afiix my signature.

EVERETT -JOEL HALL.

